Pike, now 50, was 18 when she and her then-boyfriend Tadaryl Shipp beat, tortured and murdered Colleen Slemmer, a 19-year-old they met at a job training camp for troubled teens in Knoxville, Tennessee.
The 1995 murder drew intense media attention after Slemmer's body was found with a pentagram carved into her chest. Pike had accused Slemmer of insulting her and trying to steal her boyfriend. Two other residents at the camp later testified that Pike bragged about the murder before and after the crime, and at one point showed them a piece of Slemmer's skull.
A year later, Pike was sentenced to death. Shipp, who was 17 at the time, was given a life sentence with the possibility of parole.
Sellars said she struggles to reconcile the woman she has known as kind and protective with the person who carried out the killing. Pike does not want her loved ones to witness the execution. "She doesn't want us to experience that," Sellars said.
Pike's defence has argued she is a victim too, and her lawyers have filed a clemency petition asking for her sentence to be commuted. Colleen Slemmer's mother has said she wants the execution to go ahead so her daughter "finally can be resting."
Only 18 women have been executed in the United States since the 1970s, compared with 1,663 men. If the execution proceeds, Pike will be the first woman put to death in Tennessee in more than 200 years.